<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Exception</title>
</head>
<body>
	<script>
		var txt = '';

		function message() {
			try {
				adddert('Welcome guest!');    // 抛出函数引用错误
			}
			catch(err) {
				txt = '错误描述：' + err.message + '\n\n';
				alert(txt);
			}
		}
	</script>
	<input type="button" value="查看消息" onclick="message()">
</body>
</html>